A few days ago I had a discussion with a collegue of mine about the movie series Alien. (it was a slow day...)

We violently disagreed on the biological aspect of Alien reproduction, even though neither one of is an actual biologist ( just two movie nerds in callcenter)

The thing is, what would be a plausible way for the facehugger to fit in the reproductifve cycle of the Xenomorph? The 'living egg' is in my opinion explainable as something like a shark egg, with tentacles grabbing something to hold onto (except for the opening 'mouth' thing on top)

Same goes for the Embryo/Chestburster, that could be explained as a larvae.

But how would a creature like the facehugger fit in? It seems like a separate creature, that grows in the egg, and after it matures it delivers the Xenomorph embryo into a (human) host. Is there an example of such a delivery in real nature?

It seems symbiotic, although the one is the offspring of the other, so the point my collegue made was that it is like a tadpole/frog transformation, but to me that didn't make sense because the facehugger just scampers off to die somewhere else once he delivered the embryo to the host.

Can anyone enlighten us? I'm very interested to learn if there is an example of somthing like this in nature

So there are lots of bugs and whatnot that basically just wander off and die once they have either fertilised the female or have laid their eggs, so it's not too implausible. Don't salmon do pretty much the same thing too?

You are focusing on what you have been told to think in the movie. Try analyzing what you “know”.

1. You have a “mother” that is laying “eggs”.2. There is no mention anywhere of fertilization AND all the other aliens seem to be “workers”.3. “Egg” is called that because of its shape and because something comes out of it. NOT because it’s actually is an egg biologically. Any egg supposed to supply nutrients required for production of an organism. This one doesn’t do it.

If I had to treat this reproduction scenario as fact, I would say that “mother” is actually is a father. “Eggs” are actually spore-like structures that release sperm which can move to find target (your facehugger) that in turn delivers its nucleus to the egg-surrogate cell (which happen to be one of human lung cell), etc…